516 



MINERALOGY. 



Oryctogno- Chemical Characters. Before the blowpipe it emits 

 an arsenical odour, and communicates a blue colour to 

 """ Y ~" borax. 



Constituent Parts. It is considered to be a compound 

 of Brown Ochre of Cobalt, Arsenic, and Oxide of 

 Iron. 



Geognostic Situation. It appears to occur principally 

 in secondary mountains, and is generally accompanied 

 with red and black cobalt-ochre, ochry-brown iron- 

 stone, and lamellar heavy-spar. 



Geographic Situation. It is found at Kamsdorf and 

 Saalfeld in Saxony; Alpirsbach in Wurtemberg; and 

 in the valley of Gistain in Spain. 



Use. It is used for making smalt, but is not so 

 valuable as the black cobalt. 



Observations. Distinguished from Umber, Bole, and 

 other minerals of the same description, by its streak 

 and softness. 



Yellow Co- 3. YELLOW COBALT OCHRE, Jameson. Gelber Erd- 

 balt Ochre, kobold, Werner. Cobalt arseniate terreuxargentifere(?) 

 Ha'tiy. 



External Characters. Colour yellow, which in some 

 varieties is grey and white. Occurs massive, disse- 

 minated, corroded, and incrusting. Frequently appears 

 rent in different directions. Internally it is dull. Frac- 

 ture fine earthy in the small, conchoidal in the large. 

 Fragments indeterminate angular, and blunt-edged. 

 Streak shining. Is soft, passing into friable. Is sec- 

 tile. Is very easily frangible. 



Specific gravity 2.677, Kirwan, after having absorb- 

 ed water. 



Chemical Characters. It emits an arsenical odour be- 

 fore the blowpipe, and colours borax blue. Appears to 

 be the purest of the cobalt ochres. Generally contains 

 a portion of silver. 



Geognostic Situation. Occurs in the same geognos- 

 tic situation an the preceding, and is almost always as- 

 sociated with earthy red cobalt, and sometimes with ra- 

 diated red cobalt, nickel-ochre, iron-shot copper-green, 

 and azure copper. 



Geographic Situation. Occurs at Saalfeld in Thu- 

 ringia ; Kupferberg in Silesia ; Wittichen in Fursten- 

 berg ; and Alpirsbach in Wurtemberg, in Swabia ; and 

 Allemont in France. 



Use. Affords a better smalt than the preceding, and, 

 owing to the silver it contains in the countries where 

 it occurs, is also valued as an ore of silver. 



AXTIMO- GENUS IV. ANTIMONY MICA, OR WHITE 

 KT MICA. ANTIMONY. 



Spiessglass-glimmer, Mohs. 



Three axes. Cleavage prismatic. Hardness = 1.5 

 2.0. Sp. gravity = 5.0 5.6. 



This genus contains one species, viz. Prismatic An- 

 timony Mica, or White Antimony. 



Prismatic i. PRISMATIC WHITE ANTIMONY, Jameson. Pris- 

 te An- masher Speissglass-glimmer, Mohs. Weiss-spiesgla- 

 serz, Werner. 



Prism unknown. Cleavage prismatic. 



External Characters Its colours are white and grey. 

 Seldom occurs massive, more frequently disseminated, 

 and in membranes ; also in distinct concretions, which 

 are coarse and small granular, and scopiform and stel- 

 lular radiated. Is often crystallized. The following 

 figures have been observed : 1. Rectangular four-sided 

 prism, bevelled on the extremities ; 2. Oblique four. 





sided prism ; 3. Rectangular four-sided table ; 4. Six- Oryctogno. 

 sided prism ; 5. Acicular and capillary crystals. The ** 

 tables are small and very small, usually adhering by V "~" r "" 

 their lateral planes, and sometimes, although seldom, 

 manipularly aggregated, and often intersecting each 

 other, in such a manner as to form cellular groups. 

 The crystals are sometimes smooth, sometimes feebly 

 longitudinally streaked, and splendent. Internally it 

 is shining, and the lustre is intermediate between pearly 

 and adamantine. The fragments are indeterminate 

 angular, or wedge-shaped. Is translucent. Is rather 

 sectile. 



Chemical Characters. Before the blowpipe it melts 

 very easily, and is volatilized in the form of a white 

 vapour. 



Allemont. 



Conslit. Parts. Oxide of Antimony . . 86 

 Oxides of Antimony and Iron 3 

 Silica .... 8 98 



Vauquelin, Hauy, t. iv. p. 274. 



Geognostic and Geographic Situations. It occurs in 

 veins in primitive rocks, and is usually accompanied 

 with the other ores of antimony. At Prizbram, in Bo- 

 hemia, it occurs along with crystallized galena or lead- 

 glance; and at Allemont, with native antimony, and 

 grey and red antimony. It has also been found in Ma- 

 laxa in Hungary. 



* ANTIMONY OCHRE, Jameson. Spiesglanzocker, Antimony 

 Werner. Ochre ' 



External Characters. Its colour is yellow, grey, and 

 brown. Scarcely occurs massive, and disseminated, 

 generally incrusting crystals of grey antimony. Is 

 dull. Fracture earthy, and sometimes inclines to ra- 

 diated. Is opaque. Is soft, passing into very soft. 

 Is brittle, and easily frangible. 



Chemical Characters Before the blowpipe, on char- 

 coal, it becomes white, and evaporates without melting. 

 With borax, it intumesces, and is partly reduced to the 

 metallic state. 



Geognostic and Geographic Situations. It occurs al- 

 ways in veins, and accompanied with grey antimony, 

 and sometimes with red antimony. It is found at Huel 

 Boys, in Endellion, in Cornwall. 



BLUE 

 IROK. 



GENUS V. BLUE IRON, OR IRON MICA. 



Eisen Glimmer, Mohs. 

 Three axes. Cleavage prismatic. Streak white ? 

 Hardness = 2.0. Sp. gravity = 2.8 3.0. 



This genus contains two species, viz. Prismatic Blue 

 Iron. 



1. PRISMATIC BLUE IRON. 

 Prism unknown. Cleavage prismatoidal. 

 This species is divided into three subspecies, viz. 

 Foliated Blue Iron, Fibrous Blue Iron, and Earthy 

 Blue Iron. 



FIRST SUBSPECIES. 



FOLIATED BLUE IRON, Jameson. Blattriches Eisen- Blue Irolu 

 blau, Hausmann. 



External Characters. Its colours are blue and green. 

 The secondary forms are the following : 



1. Broad rectangular four-sided prism, in which the 

 lateral edges are truncated, (the truncating planes are 

 set obliquely on the smaller lateral planes, and are the 

 original planes of the oblique four-sided prism,) flat- 

 ly bevelled on the extremities ; the bevelling planes 

 set obliquely on the broader lateral planes. 2. Eight- 

 sided prism, acuminated with four planes. The crys- 



